1. Field of the Invention
The present invention relates to the biodegrading of amine compounds. More particularly, the present invention is a process for biodegrading diethylenetriamine. Most particularly, the present invention provides for the process for the continuous fed-batch biodegradation of Decontamination Solution 2 (DS2).
2. Brief Description of the Prior Art
The safe disposal of hazardous wastes is a significant societal problem. Private industry and governmental agencies must adhere to ever increasing strict laws and regulations regarding the disposal of these hazardous wastes. As such, innovative processes are needed to reduce or eliminate hazardous waste.
Biodegradation of organic compounds using microorganisms is known. Organisms use chemicals as a source of nutrient for survival. Depending on the elemental composition, the chemicals may be used as a source of carbon, nitrogen, or phosphorous for cell propagation. In using the chemicals, the microorganisms may convert toxic chemicals into benign chemical forms. However, microorganisms must possess the necessary enzymatic systems for particular chemical compositions.
Decontamination Solution 2, or DS2, is a chemical warfare decontaminating solution used by the United States Army. DS2 contains approximately 70% diethylenetriamine (DETA), 28% ethylene glycol monomethyl ether (EGME), and 2% NaOH by weight, and is used for decontaminating a variety of chemical warfare agents. However, DS2 is toxic, flammable and hazardous to the environment. EGME is teratogenic, and the secondary amine structure in DETA possess a possible health hazard from conversion to a potential N-nitrosoamine carcinogen. DS2 is extremely resistant to biodegradation, particularly with regard to the DETA component of the solution.
Low molecular weight primary, secondary and tertiary amines have been shown as a sole source of carbon for Pseudomonas aminovorans and readily oxidized by cell extracts (Eady et. al. 1971). However, higher molecular weight secondary linear and cyclic amines have been shown to be recalcitrant and toxic to microorganisms (Emtiazi and Knapp, 1994). Several forms of secondary or tertiary amine compounds which contain one or more carboxylic groups have been shown to be biodegraded by Chelatobacter heintzii ATCC 29600 and other bacterial species, and the responsible genes have been cloned and expressed (Knobel et. al., 1996). However, the biodegradability of secondary or tertiary amines which lack such carboxylic groups as in DETA is not known.
In view of the foregoing, degradation of DS2, particularly the DETA component of DS2, in a bioreactor or in situ is desirable.
The present invention addresses these needs.